Let's start with the easiest one: The Schieder Commission or as its full title in German calls it the Dokumentation der Vertreibung der Deutschen aus Ostmittel- und Osteuropa in den Jahren 1945 bis 1948 was a project headed by German historian Theodor Schieder intended to compile material for future peace negotiations with the Allies (during the Cold War Germany never had an official peace treaty, that was only concluded when the 2+4 treaty stood in lieu of a formal peace treaty) that should stake German claims especially against the Soviet Union.

Schieder and his colleagues were instructed to provide material that proved the "bolshevik origin" of the expulsion of the Germans. Despite this concept being criticized as too one sided by German parliamentarians, the Schieder Commission was in essence a political project that had to match its findings with political expectations of the then government of Western Germany. That this was the case is evidenced by both the German government pressuring their own Federal Archive to match the numbers laid out by the Schieder Commission as well as the refusal of the West German Government to publish the last volume of the total 6 produced by the Schieder Commission because it was too explicit about the role German resettlement and Lebensraum policies played.

And before I get to that, Lebensraum and resettlement was something Schieder and his colleagues on the commission were quite adept in. Adolf Diestelkamp, who as historian Robert Moeller points out, was quite explicit that the commission's purpose was to win back German territories in the East had previously been a member of the Historical Commission for Pomerania that provided material to Nazi authorities which villages and town had to be cleansed of Poles in Pomerania. Werner Conze, also part of the Commission, had prepared documents for the German Abwehr on the "dejewification" of Poland, had been working on concrete plans for the germanficiation of Polish territories and had expressed that the Polish populationwas degenerate and and blamed lack of progress on Jews. Schieder himself had even been more crucial. He had been the author of part of the Generalplan Ost. I have written on this document here but in essence it was the masterplan for the Germanization of Eastern Europe, including the massive settlement of Germans in these territories and letting the native population starve in order to support these German settlers. The GPO envisioned 30 million people dying of starvation and while these steps were never taken, it is still a document that is planning genocide. And the guy who headed this commission co-wrote it.

So, Schieder and many of his influential colleagues in this commission had been Nazis directly involved in planning genocide and ethnic cleansing in Eastern Europe. Now that the war was over they applied their expertise in population statistics to deliver politically desired outcomes. Thanks to the recent work by historians Robert Moeller, Ingo Haar, and Rüdiger Overmans we know that the Schieder Commission inflated and doctored their numbers.

First, they included people who either worked for the occupation in Poland or were resettled there as part of the grand Nazi scheme of de-Nazification. Their metric lead to people like Erika Steinbach, one of two German politicians who voted against the Oder-Neiße Border in 1991, to be classified as a refugee – her father had been a Luftwaffe technician working at an airfield in Poland. Similarly, Rudolf Höss probably counted among their dead since he too was a German in Poland during the war who was killed by Poles.

Second, they simply counted all those missing and where further evidence wasn't available as dead. The Federal German Archive conducted an internal study in 1974 that found that there was only ever indications for at maximum 600.000 deaths resulting from expulsion and forced labor for German POWs in the Soviet Union. The report by the Federal Archive was purposefully never released. Numbers by the International Tracing Service of the Red Cross are that there are about 400.000 confirmed deaths from expulsion and so modern studies put it in the region of about half a million. The Tracing Service further listed 1.9 million people as missing; a number, which Schieder just counted as dead summarily. Additionally, the Schieder Commission in some cases also tended to count children yet unborn as casualties with the argument of declining fertility.

Thirdly, when the Federal Office of Statistics of West Germany also conducted an investigation into the matter, they too found only at most 500.000 confirmed cases of death. However, the West German government according to Ingo Haar put pressure on them to match the Schieder reports' findings and so the Stastics Office too put out the 2 million as official with the real numbers only being released in 1988.

And finally, when the final report of the Commission was too explicit about previous Nazi Lebensraum policies and their connection to the Germans being expelled after the war, it was scrapped by the West German government in form of the Ministry for the Expelled, itself headed by a former Nazi Lebensraum politician, and never published.

As for why ethnic Germans were expelled from a variety of Eastern European countries, one of the reasons becomes pretty clear when reviewing the original intention of this report, to gain control again over territory: The Nazis had used the ethnic Germans in a variety of countries as a pre-text to invade said countries and set up their rule there. Most notably in both Czechoslovakia and specifically Bohemia and Moravia as well as in Danzig vis a vis Poland. People like the post-war PM of the CSR, Edvard Benes, understood the policy of expelling Germans from Czech lands as a safeguard against future German claims on their territory. He wanted to prevent another possible Munich agreement with ethnic Germans used as pre-text for a German land grab. And a similar policy was in effect in Poland with the added caveat that there, it was also about security claims on territory freshly gained as well as getting rid of Nazi settlers that had taken Polish property from Polish citizens.

Furthermore, in cases like that of Steinbach and others, many of the Germans fled these areas from the advancing Red Army for fear of retribution and violence it would enact. So many later invoking a legacy of being expelled, actually left the area in 1944/early 1945.

Still, the way these policies were enacted both as a matter of state policy and on the ground was very violent and gruesome affair that did indeed cost many people their lives. However, it's extremely difficult to divvy up those who fled from those who were expelled and the Schieder Commission is certainly not a trustworthy source.

Sources:

*Rüdiger Overmans: Personelle Verluste der deutschen Bevölkerung durch Flucht und Vertreibung.

• Robert G. Moeller,: Driven into Zeitgeschichte. Historians and the 'Expulsion of the Germans from East-Central Europe'.

• Ingo Haar, Michael Fahlbusch: German scholars and ethnic cleansing, 1919-1945

• Ingo Haar: "Bevölkerungsbilanzen" und "Vertreibungsverluste".